The display screen and the touch screen for the currently widely available mobile phones, personal digital assistants (PDAs), and 3C products (including Computer, Communication, and Consumer electronics) with audio/visual (AV) device are made by laminating at least two different types of substrates together. FIG. 1 shows a conventional way of laminating two substrates together. As shown, a target substrate 1 has a laminating surface 11, on which a layer of optical adhesive 12 is applied. To laminate a flexible substrate 2 to the laminating surface 11 of the target substrate 1, a roller 3 is rolled in a direction I to apply a pressing force II against the flexible substrate 2, so that the flexible substrate 2 is gradually laminated to the laminating surface 11 of the target substrate 1 via the optical adhesive 12 when the roller 3 rolls. Meanwhile, air between the two substrates 1, 2 is expelled from an open end between the two substrates 1, 2.
The above-described conventional way of laminating two substrates together using a roller is disadvantageous because the roller is a mechanical device having limited cycle time for laminating only limited number of substrates together. Moreover, laminating with a roller would result in an edge effect, in which gas is trapped at a laminating interface to form bubbles that adversely affect the quality of the laminated substrates. To overcome these disadvantages, some other laminating skills have been developed. For example, U.S. Pat. No. 6,106,665 disclosed an apparatus for making ophthalmic lenses. With the apparatus, a composite lens formed from two wafers and having an optical curvature is received in an airtight enclosure formed between an upper and a lower flexible transparent sheet, and a vacuum pump draws the upper and lower flexible sheets into engagement with the composite lens to press the wafers together. Thereafter, an ultraviolet (UV) lamp is used to irradiate and cure an adhesive layer between the two wafers to form the composite lens.
And, U.S. Pat. No. 5,501,910 discloses a technique for forming a sandwiched structure comprised of a glass sheet, an adhesive layer, and a plastic film in a vacuum bag. In addition to the use of vacuum technique, a metal cover plate applying a pressing force is also used to assist in the laminating of the glass sheet to the plastic film.
The lamination disclosed in U.S. Pat. No. 6,106,665 is conducted within a ring plate, and, the lamination disclosed in U.S. Pat. No. 5,501,910 is conducted in a vacuumed bag. Neither of the above two US patents provides a stable laminating fixture. As a result, the substrates are subjected to misalignment in the process of lamination.
Moreover, the above two US patents use only the vacuum pressure and/or the pressing cover plate to assist in the lamination of two different substrates together. There is not included any other mechanism that may apply an additional external force to the substrates for the substrates to be more tightly laminated together.
It is also noted U.S. Pat. No. 6,106,665 is designed to apply in making ophthalmic lenses only, but it is not appropriate to use in the production of display screens and touch screens or the lamination of other different substrates.